Genotypic and phenotypic diversity of Mycobacterium tuberculosis complex genotypes prevalent in West Africa
Loading...
Date
2021
Journal Title
Journal ISSN
Volume Title
Publisher
PLOS ONE
Abstract
Findings from previous comparative genomics studies of the Mycobacterium tuberculosis
complex (MTBC) suggest genomic variation among the genotypes may have phenotypic
implications. We investigated the diversity in the phenotypic profiles of the main prevalent
MTBC genotypes in West Africa. Thirty-six whole genome sequenced drug susceptible
MTBC isolates belonging to lineages 4, 5 and 6 were included in this study. The isolates
were phenotypically characterized for urease activity, tween hydrolysis, Thiophen-2-
Carboxylic Acid Hydrazide (TCH) susceptibility, nitric oxide production, and growth rate in
both liquid (7H9) and solid media (7H11 and Lo¨wenstein–Jensen (L-J)). Lineage 4 isolates
showed the highest growth rate in both liquid (p = 0.0003) and on solid (L-J) media supplemented
with glycerol (p<0.001) or pyruvate (p = 0.005). L6 isolates optimally utilized pyruvate
compared to glycerol (p<0.001), whereas L5 isolates grew similarly on both media (p =
0.05). Lineage 4 isolates showed the lowest average time to positivity (TTP) (p = 0.01; Average
TTP: L4 = 15days, L5 = 16.7days, L6 = 29.7days) and the highest logCFU/mL (p = 0.04;
average logCFU/mL L4 = 5.9, L5 = 5.0, L6 = 4.4) on 7H11 supplemented with glycerol, but
there was no significant difference in growth on 7H11 supplemented with pyruvate (p =
0.23). The highest release of nitrite was recorded for L5 isolates, followed by L4 and L6 isolates.
However, the reverse was observed in the urease activity for the lineages. All isolates
tested were resistant to TCH except for one L6 isolate. Comparative genomic analyses
revealed several mutations that might explain the diverse phenotypic profiles of these isolates.
Our findings showed significant phenotypic diversity among the MTBC lineages used
for this study.
Description
Research Article
Keywords
Genotypic, Mycobacterium tuberculosis, West Africa, genotypes, genomic variation
Citation
e0255433. https://doi.org/10.1371/journal. pone.0255433